Sand blast apparatus



Sept. 13, 1932. D. s. SAMMIS 1,877,255

SAND BLAST APPARATUS Filed Oct. 3, L929 2 Sheets-Sheet l V INVENTOR DONALD S. SAMMIS 5 7 71,2; azzarzze ys- Sept; 13, 1932, D. s. SAMMIS 1,877,255

' SAND BLAST APPARATUS Filed 00:}; 5, 1929 2 Sheets-Sheet 2 Tic}.

INVENTOR DONALD S. SAMMIS 3 72/219 a/ZZarne 5 Patented Sept. 13, 1932 DO ALD s. sAMMiso'E "srnn'rronn, CONNECTICUT, ASSIGNOR mo THE NEw' HAVEN SAND BLAST o rANnor' NEW HAVEN, CONNECTICUT, A GORPORATION E oN- known practice.

NEGTICUT p p m I ,sANn ELAs'r An object ofthe. invention is toprovide i.

sand blast apparatus whichwill act automatically in a more efiicient manner than has been possible in the past, A further object is the provision of an air'valve which will control separatelyand in f proper: se

-- Fig, 3 is a longitudinal section of the valve,

and 1 Fig. 4 is a section through the valve on the lineer iof-Fig; 3., .7 1 I g The invention contemplates the combination of a novel air valve with a, sand bin, a sand tank,.a sand bin valve, and other parts, together with connections between the air valve and these parts, thegcombination functioning in a novel and highly desirable manner. 7, v y 7 In the example illustrated, there is shown a sand blast apparatus comprising-a sand bin 10, asandtankll, and a sand bin valve 12. between the sand bin and the sand tank, all constructed, generally 1 in accordance with. A mixing chamber 13 or pick up chamber, is also shown. There is likewise shown a. novel airi valve 14:, a connection .15 between the air valve 1 1 and the sand binvalve 12, a separate connection 16 between the air valve andthe sand tank-11., and another connection 17' between the air valve and the mixing chamber 13. l I

The preferred type of air valve isa piston valve, and such a valve is here illustrated and described by way of example. However, I do not desire to be limitedtoapiston valve.

The air valve 14 .here shown comprises a casting formed in two cylinders, a working cylinder 18, and: an equalizing cylinder 19. Each cylinder. has-- a pressure end, and an open end which is at all times at atmospheric pressure. Two pistons '20" and 21;, respectively, reciprocate in these two cylinders,

asameans for draining-them. I p All under pressure enters the pressure end with the sand bin valve is closed. Its action APPARATUS 1929. Serial No. 397,103.

The two pistons are connectedby a stem T l F CEii and reciprocate together. They are dis placed by alever 23-conne'cted to the stem 22 and swinging over a rack 24. The piston 20 shown on the left in Fig.3is the working piston, and the piston21 shown on the right in Fig. 3 is the equalizing piston. A connection 25 between theop posite ends of the twocylinders, 18 and 19 equalizes the pressure in both directions in. well-known manner and permits operation-ofthe air valve bymeans of the lever '23 withouttheuseof undue-force.

p I may provide plugs 26 in the two cylinders of the working cylinder 18 through .a pipe 27 (and the pressure is, of course, transmitted throughthe connection 25 tothe pressure end of the equalizing cylinder 19) As the working piston isdisplaced to the right from theta",

osition illustrated in Fi 3 .airunder ressure is admitted to the connection 15 between the air valve and the-sand bin valve, and'also; to the connection 17 between the air valve and the mixing chamber.; the same time the working piston closesathe separate connection 16 between the air valve andthe sand tank, which is open to atmosphere-when the working piston 20 is in the position shownin Fig. 3. Obviously, if the working piston were moved a sufficient distanceto'the. right it would admit pressure to the connection 16 between the air valve. and the'sand-valve. 1

By moving-thepistonin the opposite 11380? tion the connection l-fiwith the-sand tank is opened and the connection lawiththe sand 'bin valve is closed. The piston 20 is thus a means "for opening the air-connection 16 with the sand tank when theai-r connection 15 permits escape of air from the sand tank, and opening of the sandzbinvalve when the supply of airto the sand bin valve is cut off. vl/Vhichever way the piston travels one-con- Ftacts-witha seat 2:8, and openszbyfdropping I int-othe sand tank below the seat.-

' of the sand tank;

fat

The preferred form of connection between the air valve 14 and the sand bin valve12 includes a pipe end 29 of the connection 15 which extends upwardly beneath and ad acent to the sand bin valve. A sleeve is atbin valve inside the sleeve 30, andthe sand bin valve will be raised until it contacts against its seat 28. When in the raised position the sand bin valve prevents passage of air out 'From the foregoing description it" will be seen thatthe air valve "is adapted to close the sand bin valve by applying pressure thereto, which is accomplished by admitting air to its connection'withthe sand bin valve.

The sleeve 30 fits closely about the pipe end 29, but does not-prevent slight leakage of air into the sand tank 11. This leakage of air.

permits withdrawal of sandfrom the sand tank through the mixing chamber 13, as w1ll be subsequently explained.

- The separate connect1on16 from the air valve to the sand tank 16, gives the-sand tank access to the atmosphere when the air valve is closed: that is to say, when the air valve is v in the position shown in Fig. 3 of the draw- V ings. As the air'valve is opened, the end of l theconnection 16, is closed by the working j sition.

piston 20. Air which leaks into the sand tank cannot then escape, but will act to fill the space left by sand which is removed from the sand tank, and to build up pressure in the sand binvalve against its seat.

' When the air valve is closed the connection 15 is closed, the separate connection 16 is opened, and the pressure in the sand tank drops to atmosphere. ;-As-the air leaks from between the pipe'end 29 and the sleeve 30 thesand bin valve 12drops into the open posand tank thus tending further jtolift the .sand bin valve and to operate the mixing chamber. The air valve, by closing the separate connection between theair valve and the sand tank, is adapted to control pressure of example,

has been said it-will be seen' picks up sand falls train the sand tank 7 into the mixing chamber. carrying the same with high velocity to the point where the sand-blasting operation is to be carried on.

Additional pressure within the sand tank will hasten the rate at which sand flows to the mixing chamber.' If there is a vacuum in the sand tank, or 1f no prov1s1on is made for all to enter the sand tank to replace the sandpassing to the mixing chamber, then thesand will not be ableto leave the sand tank and It is preferredto form the entrance from the valve into the mixing chamber connec- 17 at a slow rate, whereas a greater movement increases the uncovered area'of the slit and the column of air moving through the mix-V ingchamber 13 will pick up no sand.

the rate at which the air is admitted to the mixing chamber. The'positionof the piston may, therefore, be regulatedto cause air to pass through'the mixing chamber at the rate desired.

Without limiting myself to the specific form of the invention'and details of construction here described and illustrated by way Iclaim: l A.

1. In a sand blast apparatus, a sand'bin, a sand tank, a sand bin valve between said sand bin and said sand tank, and almixing chamber operatively associated with said sand tank, in combination with an air valve, a connection between said air valve and said sand bin valve, a separate connection between said air valve and said sand tank, and another connection between said air valve and said mixing chamber, said air valve being adapt ed to apply 7 air pressure to said" sand bin valve connection to closesaid sand bin valve, while holding pressure within said sand tank by closing said connection between said air valve and said sand'tank. J

2. In a sand blast apparatus, a sand bin, a sand tank, a sand bin valve between said sand bin and said san'dtank, and a mixing chamber operatively associated with-said sand tank, in combination with a piston'valve, a V

connection between said piston valve and said sand bin valve, a separate connection --be tween said piston valve and said sand tank,

and another connection between said piston valve and said-mixing chamber, said piston valve being adapted to apply air pressure to said connections to close" said sand bin valve,

and to cause air to pass through said mixing chamber while holding pressure within said sand'tank. I

3; In a sand blast apparatus, a sand bin, a sand tank, a sand bin valve between said sand bin and said sand tank, and a mixing chamber operatlvely associated with sa1d sand tank, in combination wlth an a1r valve,

a connection between said air valve and said 7 sand bin valve, a separate connection between said air valve and said sand tank, and a slit connection between said air valve'and said mixing chamber, said air valve being adapted to apply air pressure directly to each of said separate connections to close said sand bin valve, to control pressure within said sand tank, and to cause air to pass through said mixing chamber at the rate desired.

4. In a sand blast apparatus, a sand bin, a sand tank, a sand bin valve between said sand bin and said sand tank, and'a mixing chamber operatively associated with said sand tank, in combination with a piston valve, a connection between said piston valve and said sand bin valve, a separate connection between said piston valve and said sand tank, and a slit connection between-said piston valve and said mixing chamber, said piston valve being adapted to apply air pres sure directly to said separate connections to close said sand bin valve, to control pressure within said sand tank, and to cause air to pass through said mixing chamber, substan tially as described.

5. In a sand blast apparatus, a sand bin, a sand tank, and a sand bin valve between said sand bin and said sand tank, in combination with an air valve, comprising a balanced piston valve, a connection between said sand bin valve and sa1d a1r valve, and a separate connection between said sand tank and said air valve, said piston valve being adapted to open said first-named connection to supply air to close said sand bin valve and close said second-named connection simultaneously to retain pressurein said sand tank.

7 6. In a sand blast apparatus, a sand bin, a sand tank, a sand bin valve between said sand bin and said sand tank, a mixing chamber, an air valve casing having a balanced piston valve therein and ports in said valve casing having separate connections to said sand tank, sand bin valve and mixing chamber, respectively, said piston valve controlling said ports to vary the supply to said mixing chamber while holding the sand bin valve closlgd and holding pressure in said sand tan In testimony whereof I have signed my name to this specification.

DONALD S. SAMMIS. v 

